Representatives of Beth Israel Deaconess Medical Center–Plymouth, Atrius Health and the New England Quality Care Alliance met with The Patriot Ledger's editorial board Tuesday to outline their opposition to the deal hammered out between Attorney General Martha Coakley's office and Partners.

QUINCY – South Shore residents are in for a tidal wave of higher health care costs and fewer options if a controversial deal to allow Partners HealthCare to acquire South Shore Hospital in Weymouth is approved, a group of Partners’ competitors say.

Representatives of Beth Israel Deaconess Medical Center-Plymouth, Atrius Health and the New England Quality Care Alliance met with The Patriot Ledger’s editorial board Tuesday to outline their opposition to the deal between Attorney General Martha Coakley’s office and Partners.

They said the deal would solidify the health care giant’s dominance and allow it to siphon off doctors from its smaller competitors, likely bringing patients with them into the state’s highest cost system.

“This is a tsunami coming down the road at these people,” said Dr. Guy Spinelli, chairman of the board of Atrius Health and president of Granite Medical Group in Quincy, referring to South Shore residents. “If this goes through in five years patients are going to scratch their heads and say, ‘Where can I get care? I can’t afford care on the South Shore because it’s a monopoly.’”

Partners and the 378-bed Weymouth hospital say merging would cut costs and improve care in the region. Under the deal, Partners would also be able to acquire Harbor Medical Associates, a medical practice with 65 physicians on the South Shore, and Hallmark Healthcare, which has two hospitals north of Boston.

“It’s the duty of the attorney general and not that of competitor third parties to protect the public interest,” said Rich Copp, a Partners spokesman. “Our competitors are not advocating for the public interest. They’re advocating for their own private interest. What’s good for Partners, they see as bad for them.”

Coakley’s office says the deal with Partners – which still must be approved by a Suffolk Superior Court judge – includes safeguards such as caps on cost growth and tight limits on expansion over the next decade that would do more to rein in Partners than trying to block the merger.

Judge Janet Sanders on Monday ordered the attorney general’s office to accept comments from the public and competitors through July 21 and then submit them with responses to the court by Aug. 1.

Sanders denied a motion by the coalition of competitors, which also includes Lahey Health System and Tufts Medical Center, to block the deal, but she left open the possibility that they could re-file it later.

On Tuesday, the competitors told The Patriot Ledger that they want the judge to reject the deal and send it back to the attorney general.

They said the price caps included in the deal would still allow Partners – the state’s largest health care provider – to increase prices faster than its competitors. Other measures, like allowing insurers to negotiate rates with separate parts of Partners rather than the system as a whole, is untested, they said.

Page 2 of 2 - “We’ve got to do something about health care costs in the state,” said Dr. Jeffrey Lasker, president and CEO of the Tufts-affiliated New England Quality Care Alliance. “This is the opposite direction from where we should be going.”

The deal has won wide local support on the South Shore, including endorsements from the mayor’s of Weymouth and Braintree, labor and business leaders, and hospital employees.

“We fully believe this agreement as filed with the court benefits the people of the South Shore and we stand firm on that,” said Sarah Darcy, a spokeswoman for South Shore Hospital.

Partners and South Shore Hospital announced plans to merge in 2012. The state’s Health Policy Commission has recommended against the deal, saying it would drive up costs and crowd out competition.

Christian Schiavone may be reached at cschiavone@ledger.com or follow him on Twitter @CSchiavo_Ledger.